1. Field of the Invention
The present invention relates to a heat pipe for carrying out heat transfer by circulating a coolant between the evaporation section and the condensation section, in particular, to a heat pipe which is capable of improving the heat transfer capacity.
2. Description of the Prior Art
In order to enhance the heat transfer capability of a heat pipe which transfers heat between the condensation section and the evaporation section, there is currently available a heat pipe that is equipped with arteries, namely, special return route for the condensed fluid from the condensation section to the evaporation section.
As examples of this type of heat pipes one may mention those shown in FIG. 1 and FIG. 2. In FIG. 1 is shown a type of heat pipe in which a mesh 12 to work as a wick is installed on the inner surface of a piping 10, and a portion of the mesh 12 is deformed to form a return route 14 for the condensed fluid. Further, in FIG. 2 is shown another type in which grooves 18 are provided in the circumferential direction on the inner surface of the piping 16, as well as a felt-like metal 20 that forms the return route for the condensed fluid is inserted in the interior of the piping 16.
However, in the prior examples shown in FIGS. 1 and 2, there exist problems concerning mechanical strength on the heat pipe such as deformation or displacement of the mesh 12 (FIG. 1) or the felt-like metal 20 (FIG. 2) in the pipe interior, caused by vibrations of some kind or other. In addition, it is extremely difficult to produce these insertions in such a way as to let them adhere closely to the inner surface of the piping 10 and 16 (FIGS. 1 and 2). Furthermore, in the case of the type shown in FIG. 1, there exists a possibility of generating a fluid film between the mesh 12 and the inner wall of the piping 10, which leads to a problem of increasing the heat resistance.
In contrast, there is a type called monogroup heat pipe, as shown in FIG. 3, in which there is provided in the container 22 a return route 28 for condensed fluid separately from the vapor passage 26 that has grooves 24 in the circumferential direction.
The type shown in FIG. 3, although the above problems can be avoided due to the fact that there exists no insertion in the pipe interior, leads to problems that the heat pipe becomes large in size and heavy in weight because of the arrangement that the vapor passage 26 and the return route 28 for condensed fluid have to be provided separately. Moreover, it has to deal with a difficult mechanical manufacturing problem, which applies also to the example shown in FIG. 2, of providing grooves 24 in the circumferential direction (in FIG. 2, it is the grooves 18 in the circumferential direction).